<asp:TemplateField HeaderText="Total price">
                <ItemTemplate>
                    <asp:Label ID="lbltotal" runat="server" Text='<%#Item.quantity*Item.price %>' ></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
 
 this column i want in totalbill 
protected void grdViewItem_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
            //totalbill += Convert.ToDecimal(e.Row.Cells[5].Text);
             //totalbill += Convert.ToDecimal((Label)e.Row.FindControl("lbltotal"));
            }
            if (e.Row.RowType == DataControlRowType.Footer)
            {
                e.Row.Cells[4].Text = "Total Amount";
                System.Globalization.CultureInfo info = System.Globalization.CultureInfo.GetCultureInfo("hi-IN");
                e.Row.Cells[5].Text = totalbill.ToString("c",info);
            }
        }